In a conventional control circuit for operating a heavy-duty electrical equipment such as a three-phase electric motor, a heavy duty type electrical relay such as a contactor, is employed. Some of the relay contacts are connected in power circuits for the motor, while others of the relay contacts are connected in a light or low current circuit that supplies current to the relay coil, to hold the coil in the energized condition. Since a large amount of current passes through the contacts in the heavy duty power circuits, there is resulting chatter of these relay contacts which produces an arc current of a sufficient magnitude to burn out dust or any objects collected between the contacts, thus eliminating contact failures. However, the contacts in the light current circuit carry a small amount of current for the relay coil, so that the resultant arc current is insufficient to burn the objects collected between such contacts.